TLS error ius

root at vagrant in ~
$ openssl s_client -showcerts -connect centos7.iuscommunity.org:443 </dev/null
CONNECTED(00000003)
depth=0 C = US, ST = Texas, L = San Antonio, O = "Rackspace US, Inc.", OU = RPM Development, CN = *.iuscommunity.org
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 C = US, ST = Texas, L = San Antonio, O = "Rackspace US, Inc.", OU = RPM Development, CN = *.iuscommunity.org
verify error:num=27:certificate not trusted
verify return:1
depth=0 C = US, ST = Texas, L = San Antonio, O = "Rackspace US, Inc.", OU = RPM Development, CN = *.iuscommunity.org
verify error:num=21:unable to verify the first certificate
verify return:1
---
Certificate chain
 0 s:/C=US/ST=Texas/L=San Antonio/O=Rackspace US, Inc./OU=RPM Development/CN=*.iuscommunity.org
   i:/C=US/O=thawte, Inc./CN=thawte SSL CA - G2
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
 1 s:/C=US/ST=Texas/L=San Antonio/O=Rackspace US, Inc./OU=RPM Development/CN=*.iuscommunity.org
   i:/C=US/O=thawte, Inc./CN=thawte SSL CA - G2
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
 2 s:/C=US/O=thawte, Inc./OU=Domain Validated SSL/CN=thawte DV SSL CA - G2
   i:/C=US/O=thawte, Inc./OU=Certification Services Division/OU=(c) 2006 thawte, Inc. - For authorized use only/CN=thawte Primary Root CA
-----BEGIN CERTIFICATE-----
MIIE0jCCA7qgAwIBAgIQLGnhL2pnC9md0g+RnvCeUTANBgkqhkiG9w0BAQsFADCB
qTELMAkGA1UEBhMCVVMxFTATBgNVBAoTDHRoYXd0ZSwgSW5jLjEoMCYGA1UECxMf
Q2VydGlmaWNhdGlvbiBTZXJ2aWNlcyBEaXZpc2lvbjE4MDYGA1UECxMvKGMpIDIw
MDYgdGhhd3RlLCBJbmMuIC0gRm9yIGF1dGhvcml6ZWQgdXNlIG9ubHkxHzAdBgNV
BAMTFnRoYXd0ZSBQcmltYXJ5IFJvb3QgQ0EwHhcNMTQwNjEwMDAwMDAwWhcNMjQw
NjA5MjM1OTU5WjBjMQswCQYDVQQGEwJVUzEVMBMGA1UEChMMdGhhd3RlLCBJbmMu
MR0wGwYDVQQLExREb21haW4gVmFsaWRhdGVkIFNTTDEeMBwGA1UEAxMVdGhhd3Rl
IERWIFNTTCBDQSAtIEcyMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA
6pQHhchBLPaDEmySX6sfANSWb3TNLhHpbA85AblIkEA5TcSiyHlqpZq9kURld1St
/yVf7kL7swIP6l163RpUntdzQpvMeV/FTfS3Cxg5IHrdUAFdNEVfTBEO9YcmJrSw
835xoDFxUIloWmOKFGLljDoWVQ0+66qAHXF644cHq72idM3aCAGdG8wniIxH1Gkl
Qta7UG2FUNBIgg0In+kj40LGPJi4u27FcBPfGR0B/dK1TuZi9Af6a30Rd8RiT0BO
pXiXqyxNDKd8w8RQMp/QcJsP//91WTSFrUnVNe5PW9TUNpWgfujFoRy9E0597mNq
lhmZyKcqAOZRjUbrMFjoLQIDAQABo4IBOTCCATUwEgYDVR0TAQH/BAgwBgEB/wIB
ADBBBgNVHSAEOjA4MDYGCmCGSAGG+EUBBzYwKDAmBggrBgEFBQcCARYaaHR0cHM6
Ly93d3cudGhhd3RlLmNvbS9jcHMwDgYDVR0PAQH/BAQDAgEGMC4GCCsGAQUFBwEB
BCIwIDAeBggrBgEFBQcwAYYSaHR0cDovL3Quc3ltY2QuY29tMDEGA1UdHwQqMCgw
JqAkoCKGIGh0dHA6Ly90LnN5bWNiLmNvbS9UaGF3dGVQQ0EuY3JsMCkGA1UdEQQi
MCCkHjAcMRowGAYDVQQDExFTeW1hbnRlY1BLSS0xLTY5ODAdBgNVHQ4EFgQUn7jB
qWzy9cAiKpTtXJms1OzXxgcwHwYDVR0jBBgwFoAUe1tFz6/Oy3r9MZIaarbzRutX
SFAwDQYJKoZIhvcNAQELBQADggEBAFNU8keoAtfvqjV4vkoIDZAYS22eKlMr6VQX
d3QpftA3BwW45Pq4tGOYRNzGT4EGjDq+xzBXxnD81pMZn8NV1z4fcoqdMFo1lzLL
Y+TGct/7aMppL9vNUDg+K7urO4LH/UubvXxBmO8BU9g1jyXJAwbmnFfBUQ+e9n2T
Tfh2yDpr9MSPMzJ/nSGENNmn+ZL6QZFhhAWdo3lGzmfngfJerEy8qKtqbRXinE5a
2WOAvPdC65pExoxrBja0izKJ3sLxqCaqqaz/6nGm54xB+hc1u7OHMamTwshY4QpO
lYOcue07pe8I4HT5wxvmB6PuB9dCInkhoKHUHSbT0NamXStBwHk=
-----END CERTIFICATE-----
 3 s:/C=US/O=thawte, Inc./OU=Certification Services Division/OU=(c) 2006 thawte, Inc. - For authorized use only/CN=thawte Primary Root CA
   i:/C=ZA/ST=Western Cape/L=Cape Town/O=Thawte Consulting cc/OU=Certification Services Division/CN=Thawte Premium Server CA/[email protected]
-----BEGIN CERTIFICATE-----
MIIERTCCA66gAwIBAgIQM2VQCHmtc+IwueAdDX+skTANBgkqhkiG9w0BAQUFADCB
zjELMAkGA1UEBhMCWkExFTATBgNVBAgTDFdlc3Rlcm4gQ2FwZTESMBAGA1UEBxMJ
Q2FwZSBUb3duMR0wGwYDVQQKExRUaGF3dGUgQ29uc3VsdGluZyBjYzEoMCYGA1UE
CxMfQ2VydGlmaWNhdGlvbiBTZXJ2aWNlcyBEaXZpc2lvbjEhMB8GA1UEAxMYVGhh
d3RlIFByZW1pdW0gU2VydmVyIENBMSgwJgYJKoZIhvcNAQkBFhlwcmVtaXVtLXNl
cnZlckB0aGF3dGUuY29tMB4XDTA2MTExNzAwMDAwMFoXDTIwMTIzMDIzNTk1OVow
gakxCzAJBgNVBAYTAlVTMRUwEwYDVQQKEwx0aGF3dGUsIEluYy4xKDAmBgNVBAsT
H0NlcnRpZmljYXRpb24gU2VydmljZXMgRGl2aXNpb24xODA2BgNVBAsTLyhjKSAy
MDA2IHRoYXd0ZSwgSW5jLiAtIEZvciBhdXRob3JpemVkIHVzZSBvbmx5MR8wHQYD
VQQDExZ0aGF3dGUgUHJpbWFyeSBSb290IENBMIIBIjANBgkqhkiG9w0BAQEFAAOC
AQ8AMIIBCgKCAQEArKDw+4BZ1JzHpM+doVlzCRBFDA0sbmjxbFtIaElZN/wLMxnC
d3/MEC2VNBzm600JpxzSuMmXNgK3idQkXwbAzESUlI0CYm/rWt0RjSiaXISQEHoN
vXRmL2o4oOLVVETrHQefB7pv7un9Tgsp9T6EoAHxnKv4HH6JpOih2HFlDaNRe+68
0iJgDblbnd+6/FFbC6+Ysuku6QToYofeK8jXTsFMZB7dz4dYukpPymgHHRydSsbV
L5HMfHFyHMXAZ+sy/cmSXJTahcCbv1N9Kwn0jJ2RH5dqUsveCTakd9h7h1BE1T5u
KWn7OUkmHgmlgHtALevoJ4XJ/mH9fuZ8lx3VnQIDAQABo4HCMIG/MA8GA1UdEwEB
/wQFMAMBAf8wOwYDVR0gBDQwMjAwBgRVHSAAMCgwJgYIKwYBBQUHAgEWGmh0dHBz
Oi8vd3d3LnRoYXd0ZS5jb20vY3BzMA4GA1UdDwEB/wQEAwIBBjAdBgNVHQ4EFgQU
e1tFz6/Oy3r9MZIaarbzRutXSFAwQAYDVR0fBDkwNzA1oDOgMYYvaHR0cDovL2Ny
bC50aGF3dGUuY29tL1RoYXd0ZVByZW1pdW1TZXJ2ZXJDQS5jcmwwDQYJKoZIhvcN
AQEFBQADgYEAhKhMyT4qvJrizI8LsiV3xGGJiWNa1KMVQNT7Xj+0Q+pjFytrmXSe
Cajd1FYVLnp5MV9jllMbNNkV6k9tcMq+9oKp7dqFd8x2HGqBCiHYQZl/Xi6Cweiq
95OBBaqStB+3msAHF/XLxrRMDtdW3HEgdDjWdMbWj2uvi42gbCkLYeA=
-----END CERTIFICATE-----
---
Server certificate
subject=/C=US/ST=Texas/L=San Antonio/O=Rackspace US, Inc./OU=RPM Development/CN=*.iuscommunity.org
issuer=/C=US/O=thawte, Inc./CN=thawte SSL CA - G2
---
No client certificate CA names sent
Server Temp Key: ECDH, prime256v1, 256 bits
---
SSL handshake has read 7071 bytes and written 373 bytes
---
New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES256-GCM-SHA384
Server public key is 4096 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : ECDHE-RSA-AES256-GCM-SHA384
    Session-ID: 46C163F0E8D46C36380E44DD06AA9A23B569C2C93D98E4F8237711A2F96730D9
    Session-ID-ctx:
    Master-Key: 55A3878BD5845B3C62F66F0282F00813CDB6168C19C3655C5BE03EB3F654527C88DA89CEB034C82F59602E1826467BA3
    Key-Arg   : None
    Krb5 Principal: None
    PSK identity: None
    PSK identity hint: None
    TLS session ticket lifetime hint: 300 (seconds)
    TLS session ticket:
    0000 - c7 fe 95 0d 79 d8 6a be-24 06 fc 0e b2 7d b4 ef   ....y.j.$....}..
    0010 - fd 7e e4 5c 1b eb b9 a3-b7 64 77 74 57 f2 fa a7   .~.\.....dwtW...
    0020 - 3e 8e 98 aa 02 c3 a2 88-76 ec 1b b4 e2 5a c3 41   >.......v....Z.A
    0030 - 5d 15 93 79 21 8c 0c 24-61 3a 5a 4f 4d fb e6 bd   ]..y!..$a:ZOM...
    0040 - 16 dd 37 e8 8a e4 78 2f-9a cd 21 2b d0 75 2c 35   ..7...x/..!+.u,5
    0050 - 4f 04 1a 7d 73 43 17 e6-45 21 fa e4 d2 03 4e e8   O..}sC..E!....N.
    0060 - c7 7a 28 cb 76 56 1d dd-df eb 7f b6 90 9a 9b d2   .z(.vV..........
    0070 - e0 b3 21 41 7a ae b2 44-7a c9 b2 21 90 9a 2d 4a   ..!Az..Dz..!..-J
    0080 - 75 b2 bb a1 94 b5 79 2f-16 a2 4d 78 05 d3 b5 57   u.....y/..Mx...W
    0090 - b9 b9 58 11 67 d3 dc 8f-cd 4d 75 94 20 5a c1 87   ..X.g....Mu. Z..
    00a0 - 53 46 e5 82 b1 a3 7a 77-0d 69 0e ad 78 97 49 09   SF....zw.i..x.I.
    00b0 - ff a0 21 ae 60 5c eb 17-66 55 84 bc d7 3b 95 b6   ..!.`\..fU...;..

    Start Time: 1457448523
    Timeout   : 300 (sec)
    Verify return code: 21 (unable to verify the first certificate)
---
DONE

What happens:

root at vagrant in ~
$ rpm -i https://centos7.iuscommunity.org/ius-release.rpm
curl: (60) Peer's Certificate issuer is not recognized.
More details here: http://curl.haxx.se/docs/sslcerts.html

curl performs SSL certificate verification by default, using a "bundle"
 of Certificate Authority (CA) public keys (CA certs). If the default
 bundle file isn't adequate, you can specify an alternate file
 using the --cacert option.
If this HTTPS server uses a certificate signed by a CA represented in
 the bundle, the certificate verification probably failed due to a
 problem with the certificate (it might be expired, or the name might
 not match the domain name in the URL).
If you'd like to turn off curl's verification of the certificate, use
 the -k (or --insecure) option.
error: skipping https://centos7.iuscommunity.org/ius-release.rpm - transfer failed

root at vagrant in ~

Same problem here